1. Field of the Invention
The present invention relates to a power source unit for an image recording apparatus such as a copying machine.
2. Description of the Prior Art
In an image recording apparatus such as a copying machine using a motor, a clutch, and a CPU (Central Processing Unit) and an IC (Integrated Circuit) which later two are associated therewith, a power source unit for outputting a plurality of different stabilized voltage values has been frequently used. The power source unit is used to drive, e.g., an electromagnetic coil such as a motor, a clutch, or a solenoid, and is also used as a power source for a plurality of high voltages. When interlayer short-circuiting or the like occurs in such coil parts, however, an overcurrent flows. Therefore, chain faults are caused, smoke or the like is emitted, and parts in associated circuits are damaged, thus exhibiting a dangerous state. Therefore, the following methods have been employed. A sensor may be additionally arranged in a terminal portion of each conventional circuit, and the sensor is connected to a CPU to perform a monitor operation. A large number of fuses are arranged in a terminal portion of each circuit to prevent the above-mentioned danger.
As described above, a monitoring method by a CPU is employed in the conventional apparatus. In this method, however, various and a large number of current and position sensors are required. Therefore, an I/O port for connecting the CPU is complicated, and cost of the circuit is undesirably increased. In addition, in a method of arranging fuses, a current value is changed depending on an operation cycle of the apparatus. Therefore, a small number of fuses are ineffective, and it is difficult to select an optimal fuse value, in practice. For this reason, a great number of fuses must be additionally arranged for components of the electronic circuit, and hence cost is increased.